New Research: Your Achilles Tendon Is an Efficient and Twisted Mess

As a physician, like every other doctor, I was taught that the Achilles was the biggest single tendon in the human body. The first day of medical school I was also told that half of everything they would teach me would eventually be proven wrong. So this past week, researchers added yet another thing that all doctors believe is true and blew it away. Turns out the Achilles isn’t one tendon but three twisted tendons! This discovery has major implications for how we fix these torn tendons, so if you’re planning on Achilles surgery, you better make sure your doctor got the memo.

The Achilles Tendon Explained

The Achilles tendon lives at the back of the ankle where it stretches from the gastrocnemius and soleus muscles (the muscles that form the calf muscle) down to the back of the calcaneus (the heel bone). The Achilles tendon is strong and thick, a bit like an industrial-strength rubber band, and for good reason: it is put under a lot of pressure every day. With every step we take, the tendon is constantly stretching and compressing. Add physical activities to the mix (e.g., sports, dance, running, etc.), and the Achilles tendon can experience enormous stress.

So why is the body’s strongest tendon so vulnerable to Achilles tendon injuries? The answer seems to lie in the fact that it’s not one tendon, but three twisted ropes.

Turns Out Your Achilles Is One Twisted Tendon!

The new study investigated specifically the forces of the three different calf muscles (soleus, lateral gastrocnemius, and medial gastrocnemius) on the Achilles tendon. What’s new about this research is that it identified that the Achilles tendon has three different and twisted subtendons. All three muscles have different functions, so this makes sense that all three connect via different tendon “ropes” to the heel bone, creating different degrees of stress on the tendon. The study suggests that it’s this “nonuniform loading” (pressure on a twisted tendon) that may make it so vulnerable to injury.

Translation? Think back to that thick industrial-strength rubber band. As a whole rubber band, it can stand up to heavy forces, but if we have smaller rubber bands that make up one whole structure and we twist them, one of those smaller and weaker bands can get loaded in a weird way and snap or become damaged.

What does all this look like? Check out the diagram below. The MG and LG parts represent the medial gastroc and lateral gastroc muscle tendons within the Achilles (inside and outside calf). The SOL part represents the soleus tendon, which is a deep postural muscle involved in standing that lives under the calf muscle. Look at the way these three subtendons twist as they go from top to bottom (proximal to distal) and you’ll get a real sense of why the Achilles is so vulnerable to injury.

Fixing the Achilles Without Surgery?

Now that we know that the Achilles is broken into subtendons, restoring normal function through surgery just got a lot harder! Now the surgeon needs to carefully align these three twisted subtendons, but since most surgeons don’t know that these exist, you’re more likely than not to end up with a misaligned tendon. Hence, if you have a partial tear or even a tear that you’ve been told is complete, it’s likely better to use a precise ultrasound-guided injection of your own platelets or stem cells to help the area heal and let the body do the heavy lifting and reconnecting of its own subtendons. However, if you do need a surgery, make sure your surgeon has gotten the memo that unless he carefully aligns these bands within the Achilles, you may well end up with an untwisted and less functional tendon.

The upshot? What’s fascinating here is that what many physicians consider is one structure, is actually not. Like the ACL and PCL ligaments in the knee, the body has developed the Achilles into parts that serve different functions. While this gives the tendon more flexibility in supporting walking, running, and jumping by more accurately transferring forces from three different muscles to the heel bone, it also creates areas of weakness as we age. In addition, it now creates much more work for any surgeon sewing a torn Achilles back together. Therefore, for most tendon tears, it’s likely better to make sure it’s aligned and then stimulate the body to heal with a precise injection of orthobiologics and let it figure out where everything goes!

FILED UNDER:

*DISCLAIMER: Like all medical procedures, Regenexx® Procedures have a success and failure rate. Patient reviews and testimonials on this site should not be interpreted as a statement on the effectiveness of our treatments for anyone else.

Chris Centeno, M.D. is a specialist in regenerative medicine and the new field of Interventional Orthopedics. Centeno pioneered orthopedic stem cell procedures in 2005 and is responsible for a large amount of the published research on stem cell use for orthopedic applications. Centeno regularly lectures on regenerative medicine and has spoken twice at the Vatican Stem Cell Conference, as well as the NFL Combine.

Customer Feedback

*DISCLAIMER: Like all medical procedures, Regenexx® Procedures have a success and failure rate. All patient reviews and testimonials on this site should not be interpreted as a statement on the effectiveness of our treatments for anyone else.

More Questions? Search the Knowledge Base.

Quick Links

Disclaimer

*DISCLAIMER: Like all medical procedures, Regenexx® Procedures have a success and failure rate. Patient reviews and testimonials on this site should not be interpreted as a statement on the effectiveness of our treatments for anyone else.